Non-contact Regions Research Articles

In vivo non-contact regions of proximal scaphoid in six extreme wrist positions

IntroductionFractures of the scaphoid are the most common carpal injuries, account for 80-90% of all carpal fractures. 5-15% nonunion of scaphoid fractures were reported even with adequate primary treatment, which probably progresses to osteoarthritic changes several decades later. Researches regarding to scaphoid physiological characteristic in vitro and in vivo and kinds of trials in clinical practice are being kept on going, which contribute much to our clinical practice. With the advancing wrist arthroscopy, 3D-print patient-specific drill guide, and intraoperative fluoroscopic guidance, dorsal approach (mini-invasive and percutaneous technique) is being popular, through which we can implant the screw in good coincidence with biomechanics and with less disturbing tenuous blood supply of the scaphoid. Investigating the noncontact area of the dorsal proximal scaphoid in different wrist positions can facilitate preoperatively estimating insert point of the screw.Materials and methodsEight volunteers were recruited to accept CT scans in six extreme wrist positions. The images of DICOM mode were imput into the Mimics analytical system, the segmented scaphoid, lunate and radius were exported in mode of ASCII STL and were opened in the software of Geomagic studio. We created four planes based on anatomic markers on the surface of the radius and scaphoid to confine the proximal scaphoid to form the so-called non-contact regions. We measured and compared the areas in six targeted positions.ResultsAmidst six extreme wrist positions, area of the non-contact region in extreme dorsal extension (59.81 ± 26.46 mm2) was significantly the smallest, and it in extreme palmar flexion significantly was largest (170.51 ± 30.44 mm2). The non-contact regions increased in order of dorsal extension, supination, ulnar deviation, radial deviation, pronation and palmar flexion. As for two-group comparison, the non-contact region showed significantly larger (p < 0.05) in palmar flexion than the others except for in pronation individually, and in radial deviation (p < 0.05) than in dorsal extension.ConclusionsSufficient space was available for the screw started from the dorsal approach despite the wrist positions.

Tibial and femoral articular cartilage exhibit opposite outcomes for T1ρ and T2* relaxation times in response to acute compressive loading in healthy knees

Abnormal loading is thought to play a key role in the disease progression of cartilage, but our understanding of how cartilage compositional measurements respond to acute compressive loading in-vivo is limited. Ten healthy subjects were scanned at two timepoints (7 ± 3 days apart) with a 3 T magnetic resonance imaging (MRI) scanner. Scanning sessions included T1ρ and T2* acquisitions of each knee in two conditions: unloaded (traditional MRI setup) and loaded in compression at 40 % bodyweight as applied by an MRI-compatible loading device. T1ρ and T2* parameters were quantified for contacting cartilage (tibial and femoral) and non-contacting cartilage (posterior femoral condyle) regions. Significant effects of load were found in contacting regions for both T1ρ and T2*. The effect of load (loaded minus unloaded) in femoral contacting regions ranged from 4.1 to 6.9 ms for T1ρ, and 3.5 to 13.7 ms for T2*, whereas tibial contacting regions ranged from −5.6 to −1.7 ms for T1ρ, and −2.1 to 0.7 ms for T2*. Notably, the responses to load in the femoral and tibial cartilage revealed opposite effects. No significant differences were found in response to load between the two visits. This is the first study that analyzed the effects of acute loading on T1ρ and T2* measurements in human femoral and tibial cartilage separately. The results suggest the effect of acute compressive loading on T1ρ and T2* was: 1) opposite in the femoral and tibial cartilage; 2) larger in contacting regions than in non-contacting regions of the femoral cartilage; and 3) not different visit-to-visit.

Influence of boron doping profile on emitter and metal contact recombination for n-PERT silicon solar cells

Increasing interest in n-type silicon (Si) solar cells due to the high-quality material properties of the n-Si wafers, their relatively low sensitivity to donor-like impurities like iron and their resistance to light-induced degradation brings more recent attention to the studies on the p+ emitter and its metal contact. In this work, we investigate the effect of the Boron doping profile on the quality of p+ emitter and their contacts with screen-printed Ag/Al metal fingers. The emitters within the scope of this study are created with BBr3 diffusion in an atmospheric diffusion furnace on n-type Si wafers and also applied to n-PERT Si cells to analyze their effects on device performance. Our results highlight the significance of the doping profile for solar cell performance, as it considerably affects the contact resistivity at the emitter-metal interface and the saturation current densities for emitter (J0, emitter) and Ag/Al metal contacts (J0, AgAl). Reducing the Boron concentration within the emitter leads to a decrease in carrier recombination in the non-contacted region of the emitter, which in turn decreases J0, emitter. However, this reduction increases the recombination in the contacted areas of the emitter, consequently elevating the J0, AgAl, and increasing the contact resistance values. Besides, the power loss analysis and simulation results based on experimental values obtained for our best solar cells group show how much J0, emitter and J0, AgAl values contribute to and would improve solar cell efficiency. The manuscript presents a case study of experimental emitter doping profile optimization applicable to similar n-type PERT or TOPCon cells with varying design parameters.

Revealing ‘invisible’ subsurface structural change/damage in silicate glass made by ‘nearly-elastic contact’ with a spherical smooth surface

This research delves into the hypothesis that elastic contact with an external object can generate `invisible' surface defects, consequently reducing the apparent load to failure, or strength, of glass. This theory, while longstanding, has left the intricate details associated with such defects largely unknown. Utilizing vibrational spectroscopic techniques—with a depth sensitivity on the order of approximately 100 nm—and chemical etching, the study investigates subsurface structural alterations in and around the area subjected to nominally-elastic contact with a Hertzian indenter. Direct contact with the spherical indenter led to the recovery of over 99.96 % of the surface topography, suggesting a near-perfect post-indentation surface. However, surface-sensitive vibrational spectroscopy unveiled structural changes in the subsurface silicate network. Additionally, a shift in the vibrational spectrum was observed in areas that had experienced elastic deformation along with the contact region and fully recovered upon unloading. This shift indicates residual structural changes, even in these non-contacted regions. When the indenter tip was slid across the surface under loads much lower than the nominal yield strength, interfacial friction made the top-most region more susceptible to base-catalyzed hydrolysis. The depth affected by friction was significantly shallower than the length scale of the principal stress fields at maximum load during Hertzian indentation. Despite the glass surface maintaining its microscopic defect-free appearance, these subsurface structural changes—induced by indentation and friction—are proposed to be key factors responsile for the decrease in the apparent load to failure of glass.

Frictional heat accumulation at cyclically rolling-sliding contacts with consideration to time-dependent contact pressure

A finite element model is proposed for analyzing the frictional heat accumulation at high-speed rolling-sliding contacts. The moving frictional heat flux as a function of the time-dependent contact pressure is applied cyclically on the contact surface. The convectional heat boundary is considered in non-contact region. The transient temperature changes on the contact surface are calculated, which is validated against analytical calculation results by employing the Fourier transform method. The frictional heat accumulation effect and equilibrium-state temperature are obtained during cyclically rolling-sliding contacts.

Simulation of electrical contact wear on the rough surfaces of ultra-high-voltage transmission line fittings

A novel electrical contact wear simulation method was proposed to characterize the electrical contact wear of fittings in ultra-high-voltage transmission lines by combining line fittings with the Archard wear model and oxidation loss theory. In this method, a three-dimensional (3D) rough body was generated by using the Weierstrass–Mandelbrot fractal function to simulate the contact surface. An electrical contact wear subroutine was developed, and the wear state was updated using arbitrary Lagrangian–Eulerian adaptive grid technology. Finally, finite element software was used to perform thermal stress wear coupled analysis. The results show that the wear volume, wear depth and friction temperature obtained by the rough electric contact model were 2.71 times, 4.21 times and 2.18 times of the common ideal plane model, respectively. In the rough model, the wear depth of the nodes initially accelerated, subsequently slowed down, and again accelerated with time. The friction high temperature region was distributed in a point pattern, and the temperature difference between the contact region and the non-contact region became obvious.

Numerical solution of dry friction in point contact using the unified Reynolds method combined with rarefied gas effect

Dry friction problems are widespread in engineering applications. However, the current research on the contact pressure between interfaces mainly relies on static contact mechanics solutions, neglecting the influence of the contact pressure generated by the gases in the environment. In this paper, the ambient gas is considered as a lubricant with lubricating effects. Drawing inspiration from hydrodynamic lubrication methods, a unified mixed lubrication equation for dry friction problems is developed, taking into account the influence of gas rarefaction effects. This study computes the dry friction contact pressure under different winding speeds and loads. The advantage of this method lies in its ability to automatically distinguish between the contact and noncontact regions during the calculation process, enabling the determination of the contact pressure over the entire contact area. The computational results demonstrate that at low entrainment velocities, there is minimal deviation in contact pressure and contact area compared to Hertzian contact. However, as the entrainment velocity increases, the actual pressure-bearing area enlarges compared to static contact, and there is a smooth transition of pressure at the contact edge, which cannot be obtained from static contact analysis. Finally, the numerical solution of the contact pressure when the sliding speed spans several orders of magnitude is given, and the calculation results show that the numerical model has good robustness. This numerical approach offers valuable insights for guiding the design of air bearings in practical applications.

On Mechanical and Motion Behavior of the Normal Impact Interface between a Rigid Sphere and Elastic Half-Space

This paper presents exact solutions for the mechanical behavior of the interface during the normal collision between a rigid sphere and an elastic half-space based on kinematics and particle dynamics theory. The interfacial contact stress is significantly different from the static solution obtained from the Hertz contact theory. Firstly, according to the kinematics theory, the elastic half-space interface deformation of the sphere and the half-space interface in the collision process is divided into the deformation of the contact area and the non-contact area. The curve of the non-contract area is strictly antisymmetric to the deformation curve of the contact area, and the lateral deformation for each particle at the interface can be neglected when the collision depth is relatively small. Then, the vertical deformation equation of the contact area of the half-space interface, the dynamic equation of the rigid sphere, and the dynamic equation of the interface particle in the contact region are established. The proportional relationship between the stress or strain of any particle in the contact area, the stress or strain of the collision center point, and the method for determining the maximum collision depth are obtained. The equal deformation depth in the contact and non-contact regions, and the proportional relationship between the stress or strain in the contact area and the center point of the collision at any moment are consistent with the Hertz contact theory, which verifies the reliability of the current study. Taking the sphere of no initial velocity collides with the half-space under pure gravity as an example, when the elastic half-space Poisson’s ratio is taken as 0.2–0.4, the ratio of the maximum contact stress determined by the Hertz theory and the current solution when the sphere reaches the maximum collision depth is 0.58–0.54. Based on this study, the contact stress and its distribution in the interfacial contact region can be obtained when the motion state of the sphere and the interface are determined.

Study on impact dynamic characteristics of semi-autogenous mill liner based on improved multivariable method

The impact resistance of semi-autogenous mill liner has an important influence on the reliable operation of the system. The complex dynamic characteristics in the process of collision with abrasive medium are studied by the improved multivariable method proposed in this paper. Firstly, based on manifold element method, the deformation of abrasive medium and lining plate in the contact area is expressed by the coordinates of first-order manifold element basis function, while the deformation of the non-contact region is described by modal coordinates to improve the traditional multivariable method, and the displacement constraint equations as well as the acceleration constraint equations of the collision system are derived, then the Lagrange method is used to establish the impact dynamic equation of abrasive medium and lining plate system. Secondly, a collision test rig between abrasive medium and lining plate was built to verify the correctness and accuracy of the proposed method. Finally, the influence of structural parameters and motion parameters of abrasive medium and lining plate on the dynamic characteristics of collision system is analyzed by parameter analysis method. It is found that when the Poisson’s ratio of abrasive medium to lining plate material exceeds 1.0, the increase amplitude of stress becomes smaller. The increase amplitude of displacement, velocity, acceleration and stress at the collision contact point decreases when the initial velocity of abrasive medium exceeds 3.0 m/s. The stress at the collision contact point changes greatly, and the maximum acceleration occurs in advance when the radius of abrasive medium exceeds 20 mm. When the thickness of liner exceeds 40 mm, the time of maximum acceleration to reach is almost unchanged. The results show that compared with the traditional multivariable method, the improved multivariable method can increase the modeling efficiency and solving accuracy, and lay a theoretical foundation for optimizing the structure of the liner and raising the service life of the system.

Press-fit analysis of multilayer interference fit

Multilayer interference fits are widely used in the machinery industry, and their performance is closely related to assembly quality. Press-fit is the primary assembly method. The pre-deformation of the previous assembly step can significantly affect the stress distribution (stress concentration) and pressing force in subsequent assembly steps. Therefore, the wear degree of the contact interface and the assembly quality of the components are affected by the assembly sequence. The multilayer thick-walled cylinder theory (MTCT) cannot realize the accurate analysis of stress distribution and pressing force during assembly. Therefore, this paper optimizes the MTCT considering the resistant force generated by the non-contact regions and proposes an assembly matrix generation algorithm and an assembly sequence optimization algorithm. Compared with the simulation analysis, the optimized theoretical model can be used for the analysis of the stress distribution and pressing force of multilayer interference components. The analysis accuracy is significantly improved compared with MTCT. The optimal assembly sequence determined by the proposed algorithm is consistent with simulation results.

Investigation on model order reduction methods for flexible bodies with contact-impact based on partition modeling

The finite element method is widely used to solve the problem of flexible bodies with contact-impact. To express the high-frequency and high-transient characteristics of the impact process and the high stress distribution of the local contact region, the amount of the node coordinates will be very large, which brings great burden to the dynamic simulation. It is particularly important to reduce the degrees of freedom of the system in the contact-impact problem. However, as the impact itself is a strong nonlinear problem, the linear model reduction techniques cannot be used directly. The partition method is presented to solve this problem, in which the deformation of the contact region is described by finite element node coordinates to preserve the local nonlinear characteristic while the deformation of the non-contact region is described by the reduced elastic coordinates. Different model reduction techniques including modal truncation method and Krylov subspace method are used to reduce the degrees of freedom of the non-contact region of an experimental rod-plate impact case, and the results are compared with that of the finite element method and the experiment. The simulation results show that the partition method can effectively reduce the degrees of freedom of the system and maintain good accuracy. Moreover, the Krylov subspace method has an advantage over the modal method in the model reduction of contact-impact problem.

Electrostatically actuated MEMS in the post-touchdown regime: The thin-dielectric limit and a novel reduced-order model for release dynamics

Microelectromechanical systems (MEMS) often make use of a type of plate-based electrostatic actuator that can, under certain conditions, come into contact with a dielectric-coated electrode. After this “touchdown,” the presence of a free boundary between the contacting and non-contacting regions of the plate induces strong nonlinearities in the system, significantly affecting its dynamics. In this paper we construct and analyze the mechanics of an idealized actuator after touchdown, focusing especially on the case where the dielectric is very thin and neglecting as many sources of nonlinearity as feasible in order to isolate the effect of contact. After characterizing the static equilibria, we construct a reduced-order dynamic model and investigate its application to the problem of vibration-assisted stiction repair, in which structural vibrations are employed to release the actuator from the touchdown configuration. This model has several features that are interesting in their own right, including a saddle–node bifurcation and finite-time blow-up. Our approach synthesizes concepts from configurational mechanics, fracture mechanics, and nonlinear dynamics, and serves as a blueprint for constructing more sophisticated models of touchdown dynamics that incorporate important practical effects.

Interdigitated back-contacted crystalline silicon solar cells fully manufactured with atomic layer deposited selective contacts

The interdigitated back-contacted (IBC) solar cell concept has been extensively studied for single-junction cells and more recently as a good choice for three-terminal tandem devices. In this work, carrier-selective contacts based on transition metal oxides deposited by atomic layer deposition (ALD) technique are applied to IBC c-Si(n) devices. In the first part of the study, we develop a hole-selective contact based on thin ALD vanadium oxide (V2O5) layers without using an amorphous silicon interlayer. The ALD process has been optimised, i.e. number of ALD cycles and deposition temperature, as a trade-off between surface passivation and contact resistivity. Noticeable surface passivation with recombination current densities around 100 fA/cm2, as well as reasonable contact resistivity values below 250 mΩcm2 are reached using 200 ALD V2O5 cycles deposited at a deposition temperature of 125 °C (∼10 nm layer thickness). The optimised ALD V2O5-based contact is combined with both an ALD TiO2-based electron-selective contact and an excellent surface passivation in non-contacted regions provided by ALD Al2O3 films, to form a fully ALD IBC c-Si(n) solar cell scheme. Fabricated devices yield photovoltaic efficiencies and pseudo efficiencies, i.e. calculated without series resistance losses, of 18.6% and 21.1% respectively (3 cm × 3 cm device area). These results reveal the potential of the ALD technique to deposit transition metal oxide (TMO) films as selective contacts on high efficiency devices, paving the way of using low thermal-budget, low cost and highly scalable processes for a highly demanding IBC solar cell architecture in the photovoltaic industry.

Investigation into movable dislocation evolution feature and strengthening effect for metal twin Al from atomic perspective

It is an universal phenomenon that the dislocations are produced in metal plastic deformation, which will has a potential value in fundamental research field for metal strengthening and toughening if its evolution characteristics and laws are investigated. Therefore, this behavior of movable dislocation for metal Al is studied by atomic simulation, and the microscopic mechanism of metal strengthening and toughening are also revealed through studying the interaction between movable dislocation induced by nano-indentation and twin boundary. Furthermore, the movable dislocation features, and dislocation density, and hardness, and adhesive effect are analyzed, and the comparison between the single boundary height and the multilayer twin boundary height is conducted. It is found that the plastic deformation of aluminum mental can be dominant by coordinating the amorphous generation and hexagonal close-packed structure under high speed deformation. In the nano-indentation process, the twin boundary has two obvious effects on movable dislocation of moving changes: one is to hinder the dislocation from migrating, the other is to induce dislocation to produce a cell, which result in the dislocation entanglement and generation of cross slip, it is also the main reason why the metal has excellent mechanical properties of strengthening and toughening features. These results demonstrate that the local non-contact region on the surface of Al substrate can induce atomic mismatch spots to appear during loading, and when the distance between the twin boundary and the upper surface of the substrate decreases, the effects of dislocation winding and dislocation slip become more obvious, and the anti-adhesion effect also decreases. In addition, the twin boundary is treated as the propagation of plastic ring source in the dislocation emission process when substrate is continuously loaded. These results provide an important theoretical source for improving metal strengthening and toughening effect.

Tuning the Surface Reactivity and Tribological Performance of Phosphonium-Based Ionic Liquid at Steel/Steel Interfaces by Bromide/Phosphate Anion Mixtures

Phosphonium phosphate ionic liquids (ILs) are promising lubricant additives for engine oils owing to a combination of good tribological performance and attractive properties, such as high thermal stability and good miscibility with mineral and synthetic oils. Here, we evaluate the dependence of the lubricating performance of trihexyltetradecylphosphonium ([P6,6,6,14])-based ILs when used in steel/steel contacts on the relative concentration of bis(2-ethylhexyl)phosphate ([DEHP]) and bromide (Br-) anions. The results indicate no changes in friction and wear upon increasing the [P6,6,6,14]Br-to-[P6,6,6,14][DEHP] volume ratio up to 0.2:1, while a further increase in this ratio leads to a reduction of friction and wear. X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry measurements highlight that the dependence of the lubricating properties of the ILs on the [P6,6,6,14]Br-to-[P6,6,6,14][DEHP] ratio originates from the balance between corrosivity and surface reactivity of this IL: while [DEHP] acts as corrosion inhibitor in the non-contact region, the formation of species containing phosphorus-oxygen moieties in the wear track as a result of the hydrolysis of phosphonium ions increases the surface coverage of phosphorus. This is proposed to decrease friction by decreasing adhesion at steel/steel contacts and lowering the interfacial shear strength.

Concentration Distribution and Stresses in Porous Electrodes with Particle-Particle Contact

During the charge/discharge cycle or fabrication, stresses which arise from diffusion-induced stress (DIS) and particle-particle contact can cause mechanical degradation or failure of Li-ion battery porous electrodes. Here, we develop a new model of porous electrodes in which shape polydispersity and different contact types are considered. The influences of particle-particle contact, contact types, and shape polydispersity on the concentration profile and stresses were numerically investigated. For only spherical-spherical contact, the Li-ion concentration in the contact region of the particles significantly decreased compared with that in the noncontact region, and there is significant radial stress located near the contact area. For purely elliptical-elliptical contact, the best contact type was obtained with the minimum stress and maximum contact radius. For arbitrary contact with shape polydispersity particles, the Li-ion concentration of pole-spherical contact near the contact point is lower, and equator-spherical contacts have a lower contact stress but higher contact radius. Moreover, contact stresses were dominant over DIS for all studied cases. With the formulation and simulation of the particle direct contact process, this study refines our understanding of the electrochemical-mechanical coupling effect in Li-ion batteries porous electrode.

Fretting Wear of Rubber Sealing Ring Caused by Fluid Pressure Fluctuation

In the process of gas charging and discharging of gas cylinder, the fluid pressure fluctuates causing fretting wear of rubber sealing ring, which affects the sealing performance. The model of O-ring that installed at the mouth of the gas cylinder was established to study the fretting wear in the static seal. Effects of fluid pressure, compression ratio, friction coefficient and temperature on the fretting wear of the O-ring were considered. The results show that the fretting wear of O-ring can be divided into non-contact region, slip region and sticky region. In the static seal, the compression ratio and friction coefficient are the main factors affecting the fretting wear. The sealing performance is greatly influenced on the compression ratio and it is less affected by the temperature. The junction of slip region and sticky region has the greatest probability of seal failure.

Dry Exfoliation of Large-Area 2D Monolayer and Heterostructure Arrays.

Two-dimensional (2D) semiconductors have attracted considerable attention in recent years. However, to date, there is still no effective approach to produce large-scale monolayers while retaining their intrinsic properties. Here, we report a simple mechanical exfoliation method to produce large-scale and high-quality 2D semiconductors, by designing an atomically flat Au-mesh film as the peeling tape. Using our prefabricated mesh tape, the limited contact region (between the 2D crystal and Au) could provide enough adhesion to mechanically exfoliate uniform 2D monolayers, and the noncontact region (between the mesh holes and monolayers) ensures weak interaction to mechanically release the 2D monolayers on desired substrates. Together, we demonstrate a scalable method to dry exfoliate various 2D monolayer arrays onto different substrates without involving any solutions or contaminations, representing the optimization between material yield, scalability, and quality. Furthermore, detailed optical and electrical characterizations are conducted to confirm their intrinsic quality. With the ability to mechanically exfoliate various 2D arrays and further restacking them, we have demonstrated large-scale van der Waals heterostructure arrays through layer-to-layer assembling. Our study offers a simple and scalable method for dry exfoliating 2D monolayer and heterostructure arrays with intrinsic material quality, which could be crucial to accelerate fundamental investigations as well as practical applications of proof-of-concepts devices.

Edge effects on the contact resistance of side-bonded contacts to heavily n-doped silicon nanowires

We significantly improve the physical understanding and theoretical estimate of the contact resistance of a side-bonded contact to heavily doped semiconductor nanowire by highlighting the edge effects. The contact can be made of metal or metal silicide . Prior model of a side-bonded contact to semiconductor nanowire (NW) estimates the contact resistance using radial tunneling in the contacted NW region, neglecting the edge tunneling and fringing field in the non-contacted NW region. Using realistic TCAD simulations, we show that: (i) edge tunneling dominates over radial tunneling as contact thickness, nanowire radius or ambient dielectric constant are reduced; hence a thin contact together with a low- k surrounding dielectric can yield a significantly lower contact resistance; (ii) fringing field reduces both radial tunneling and edge tunneling.

Nontribological corrosion modes dominate wrought CoCrMo acetabular taper corrosion: A retrieval study.

Corrosion of modular metal-on-metal acetabular tapers in total hip arthroplasty (THA) systems is often attributed to mechanically driven processes. Recent findings suggest that mechanically assisted crevice corrosion (MACC) might not be the dominant cause of corrosion in shell-liner tapers. This study aims to document and present the corrosion modes observed in metal-metal acetabular liners. Twenty-one retrieved wrought CoCrMo liners were examined using digital optical microscopy (DOM), scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS). Corrosion-related damage was documented in nonengagement taper regions, outside of direct taper contact. Within engagement regions, nonmechanically driven corrosion features (pitting, intergranular corrosion) were observed adjacent to fretting and material transfer, which rely on mechanical contact; corrosion independent of MACC was observed even in contact regions. Corrosion types observed included intergranular corrosion (IGC), pitting attack, phase boundary dissolution, all both outside and inside of taper junctions, and MACC within contact regions of the taper. Typical fretting scars associated with MACC were mostly absent, and were not always associated with corrosion damage where present. Finally, hard phase particles (Mo-Si-O) released from the wrought CoCrMo microstructure had redeposited within regions with material loss. Acetabular taper corrosion modes differ significantly from those in head-neck tapers and are dominated by electrochemically driven processes, not mechanical processes, as indicated by corrosion in noncontact regions. With greater prevalence of dual mobility hip implants, acetabular taper corrosion processes must be understood in order to limit their impact on device performance.